intussusception

Question 1

Define

Answer 1

Describes the invagination of proximal bowel into the distal segment

Most commonly involves the ileum passing into the caecum through the ileocaecal valve (ilio-colic)

It is the MOST COMMON cause of intestinal obstruction in infants after the neonatal period

Intussusception usually affects infants between 5-12 months old.

Boys are affected twice as often as girls

Question 2

Aetiology

Answer 2

Usually NO underlying intestinal cause

Lymphoid hyperplasia in the bowel wall can occur as a result of weaning and enteric viral infections

A viral infection (e.g. rotavirus, adenovirus) leading to enlargement of Peyer’s patches may form the lead point of the intussusception

Stretching and constriction of the mesentery  venous obstruction  engorgement and bleeding from the bowel mucosa, fluid loss  bowel perforation, peritonitis and gut necrosis

Other possible lead points include a Meckel’s diverticulum or polyp (more likely in children > 2 years old)

Intussusception requires prompt diagnosis, immediate fluid resuscitation and urgent reduction of the intussusception

Associated conditions: Henoch-Schonlein purpura (intestinal wall haematoma), cystic fibrosis (hypertrophied mucosal glands) and lymphoma

Question 3

Symptoms

Answer 3

Peak age of presentation: 3 months- 2 years

CLASSIC TRIAD: vomiting, bloody stools and abdominal pain (colic)

Paroxysmal, severe colicky pain with pallor

During episodes of pain, the child becomes pale, especially around the mouth and draws their legs up

Draw up into a ball

There is recovery between the episodes but the child may become lethargic

Happy then screaming then happy then screaming etc

Vomiting which may become bile-stained depending on the site of the intussusception

Sausage-shaped mass on physical examination (25% of patients) – found in RUQ

Dance’s sign = emptiness on palpation in RLQ

Passage of a redcurrant jelly stool (blood-stained mucus)- CHARACTERISTIC sign (but tends to occur in later illness)

Refusing feeds

Abdominal distension

Shock - assess as small chance of perforation

Question 4

Investigations

Answer 4

Investigations

Abdominal USS (DIAGNOSTIC) is useful to confirm the diagnosis (‘target sign’ or ‘doughnut sign’) and check the response to treatment

X-ray may show distended small bowel with NO gas in the distal colon and rectum

paucity (less) of air in RUQ + large bowel, thickened wall (oedema), poorly defined liver edge, dilated small bowel loops

• There is a mass and paucity of bowel gas in the right upper quadrant causing loss of clarity of the liver edge. This represents the intussusception. 
•  The intussusception is likely to be ileo-colic due the position in the RUQ; the dilated loops of small bowel proximal to the intussusception and paucity of gas within the deflated large bowel distal to the obstruction.
• An abdominal X-ray is essential to look for free air if the patient has signs of peritonitis and may have perforated.
  NOTE: sausage shaped mass

Question 5

Management

Answer 5

ABCDE Approach - EMMERGENCY

REFER TO PAEDS SURGEONS

IV fluid resuscitation- likely to be needed as there is often pooling of fluid in the gut which could lead to hypovolaemic shock

NBM + NG tube aspiration may be needed

Unless there are signs of peritonitis, reduction of the intussusception by rectal air insufflation (with fluoroscopy guidance) is usually attempted by a radiologist

• Air is introduced under pressure through a rectal catheter. A manometer monitors the pressure and this should not exceed 110mmHg. The air pressure meeting the intussusception usually forces the inverted bowel back through the ileo-caecal valve and into its expected position. This is visualised under fluoroscopic (X-ray) control.
• Success rate is 75%
• Remaining 25% require an operation

Clinically stable with no contraindications to contrast enema reduction:

Fluid resuscitation

Contrast enema (air or contrast liquid)- Barium or Gastrograffin enema
* Under light GA, dilute barium is trickled into the rectum under a hydrostatic pressure < 30cmH2O. Screening identifies the position and features of the intussusception. The pressure is maintained for a period (< 30 minutes) before re-screening to assess reduction of the intussusception

Contraindications
* Peritonitis
* Perforation
* Hypovolaemic shock

Broad-spectrum antibiotics
* Clindamycin + gentamicin OR tazocin OR cefotixin + vancomycin

2nd Line: surgical reduction + vancomycin

If peritonitis- surgery is required
* Must give prophylactic AB
* Surgical reduction

If recurrent intussusception- consider investigating for a pathological lead point (e.g. Meckel’s diverticulum)

Question 6

Complications

Answer 6

Complications

MOST SERIOUS COMPLICATION: stretching and constriction of the mesentery resulting in venous obstruction, causing engorgement and bleeding from the bowel mucosa, fluid loss and eventually bowel perforation, peritonitis and gut necrosis.

Recurrence risk of 5%

If recurrent intussusception – consider investigating for a lead point (Meckel’s diverticulum, polyps, appendix)